. The Quarterly journal of the Geological Society of London . deltoidea of Brut dale and Mont des Boucards, 10 m. Cokallian. Ar. Coral Rag with Cidaris fiorigemma of Limestones with Tsocardia. ) Limestones of Mont des Bou-B. Limestones with Terebratul®. I cards —Pyritous clays and hme-A. Coral Rag with Cid. fiorigemma. J iXlis 50 m Upper limestone with Pseudomelania heddinqtonensis, 1 m. Clays with Ammonites Martelli and sponges, H m. Middle and limestones with Ostrea dilatata, 5 clays of Wast, 6 m. Lower Oxfordian (Callovian).Fissile li
. The Quarterly journal of the Geological Society of London . deltoidea of Brut dale and Mont des Boucards, 10 m. Cokallian. Ar. Coral Rag with Cidaris fiorigemma of Limestones with Tsocardia. ) Limestones of Mont des Bou-B. Limestones with Terebratul®. I cards —Pyritous clays and hme-A. Coral Rag with Cid. fiorigemma. J iXlis 50 m Upper limestone with Pseudomelania heddinqtonensis, 1 m. Clays with Ammonites Martelli and sponges, H m. Middle and limestones with Ostrea dilatata, 5 clays of Wast, 6 m. Lower Oxfordian (Callovian).Fissile limestones with Ammonites Lamberti, 2 with Ammonites Duncani, 6 clays with Ammonites calloviensis, 5 m. JTJEASSIC OF THE PAEIS EASIN. 559 This classification is the result of several modifications of pre-vious ones, especially in the matter of names. The Upper Jurassic strata in the Boulogne area lie in an anti-clinal whose crest has a slope from to Hence the Pig. 16.—Map of Part of the Boidonnais. (Scale 1 : 240,000.). lowest strata are seen in the corner, and the succession maybe traced by passing thence to the sea at Boulogne, whence a diver-gence to the right or left will show the uppermost portions. Thedevelopment is also greater towards the , as in the contrarydirection we approach the shore-line. Erom M. Pellats beds E.,or the base of the Nerinsean limestones, downwards, the prevail-ing character is argillaceous, and the comparatively feeble lime-stones are merely intercalated masses, themselves usually more orless marly. This feature renders the correlation somewhat difficult,and has given rise to the complicated classifications of MM. Pellatand Bigaux. The lower groups of clays, estimated by M. Pellat at 26 metresin the north, but at 47 metres in the south-west, have not been spe-cially examined. The uppermost portion, with Amm. cordatus andMillericrinus, doubtless corresponds to the iSothe grits and clays, and 560 J. P
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